In recent years, combination radio-cassette tape records/players have begun rapidly enjoying wide acceptance. This radio-cassette tape record/player must have a large power output have high fidelity (HiFi) and incorporate many different functions.
In the field of audio equipment, it is desired to develop a device which can automatically select a desired music piece from among those recorded in a magnetic tape and allow the user himself (or herself) to enjoy the music and, if desired, to sing along. Also tape record/players using a tape recording of an orchestral accompaniment devoid of a vocal performance are enjoying an unprecedented boom.
The radio-cassette tape record/players must be able to produce a vocal-free orchestral relatively easily. A known cuing apparatus or an automatic music piece selector developed from said curing apparatus enables the ordinary tape recorder/player to meet the this requirement with relative ease. However, a tape recorder/player with such an apparatus must not simply cope with a demand for the production of a vocal-free orchestral accompaniment, but it should also be capable at the same time of carrying out any operation mode reliably without an erroneous behavior such as a failure to select a desired music piece.
The known automatic music piece selector (even a simple cuing apparatus is regarded as similar to such a selector) comprises a coincidence detector which counts detection pulses issued from an inter-music piece space detector (the inter-music piece space detector detects a signal-free space between the respective adjacent music pieces), compares the counted number of detection pulses with a value preset in a designator of the sequential number of a music piece (hereinafter referred to as a "music piece sequence designator"), and sends forth a coincidence signal when the compared numbers accord with each other or indicate a prescribed conforming relationship.
The above-mentioned automatic music piece selector automatically selects a desired music piece by actuating an electro-mechanical conversion mechanism, such as a plunger, by said coincidence signal and changing over the operation mode of a tape recorder or player.
This automatic music piece-selecting operation is carried out by letting a tape transport proceed at high speed (fast forward or rewind mode) until a specified or desired music piece is detected, stopping the high speed tape transport after detection of a desired music piece, and finally changing the operation mode to the specified speed of the tape transport (playback mode).
The above-mentioned conventional automatic music piece selector automatically selects only one music piece by a single operation. An operation of detecting an inter-music piece space is undertaken while the tape is made to run at high speed. Therefore, said conventional music piece selector is only capable of carrying out the simplest function among those which are possibly effected by such device.
Moreover, the prior art music piece selector had the serious drawback that a device for detecting a space between adjacent music pieces or data recorded in a tape (hereinafter referred to as a "space detector") sometimes failed to detect the space. The known space detector comprises a clipper which amplifies a playback signal up to a clipping level, a rectifier which rectifies an output signal from the clipper, a Schmitt trigger which distinguishes between the levels of rectified outputs from the rectifier, and a differentiating circuit which converts an output from the Schmitt trigger into a pulse signal. The above-mentioned prior art space detector is generally of the type which generates a pulse signal for each space between adjacent music pieces or data recorded in a tape by utilizing the different levels of signals denoting a recorded signal portion representing a music piece and a signal-free space between adjacent recorded music pieces or data. The arrangement of such a space detector is set forth in the Japanese Patent Disclosure No. 152,210 (1977) on an apparatus for detecting a space between adjacent music pieces recorded in a tape used with a tape recorder.
There are two reasons that the prior art space detector failed to reliably detect an inter-music piece space, possibly leading to an erroneous action. One of these two reasons is low frequency noises such as hums which generally arise from a signal-free space between adjacent music pieces recorded in a tape. Where a tape runs at a high speed for detection of an inter-music piece space, these low frequency noises are undesirably reproduced with a high level and at an appreciably high frequency of, for example, about 3 KHz. Such high frequency noises arising from the signal-free inter-music piece space are sometimes detected without being distinguished from music signals. Therefore, the space detector fails to reliably detect an inter-music piece space.
The other of the two reasons is related to the timing in which the changeover mechanism of a tape recorder is actuated for a desired operation mode. When a tape player is changed over from the playback mode to the fast forward mode (FF mode) for the purpose of selecting a music piece while another music piece is still being reproduced, coincidence of the space count and the preset value does not always take place between the point of time at which the mechanical system begins to be operated and the point of time at which the electric system begins to be actuated.
The conventional space detector controls the operation of a tape recorder by an output denoting the detection of an inter-music piece space (strictly speaking, a signal showing a coincidence between a connected number of pulses issued from the space detector and a value preset in the music piece sequence designator). At this time, the operation of the space detector is controlled by a discrimination signal whose logic level varies with the operation mode of the tape player mechanism. For example, is set at "1" at the time of, for example, the playback mode, and at "0" at the time of the fast forward (FF) mode. If, therefore, no coincidence is ensured between the time when the mechanical system of a tape recorder begins to be operated and the time when the electric system thereof begins to be actuated, then the space detector undesirably takes an erroneous action.
Another problem is that where an electro-mechanical conversion mechanism, such as a plunger driven by a signal denoting an inter-music piece, space is actuated, then the so-called plunger noises arise, sometimes causing the space detector to take an erroneous action.
In recent years, an automatic, highly advanced music piece selector has been required to pick up not merely only one music piece, but also a plurality of music pieces at once. This requirement further aggravates the aforesaid difficulties. Moreover, a new problem characteristic of the selection of plural music pieces is now brought about. Where a single music piece is to be selected, it is usually sufficient if an inter-music piece space is detected simply by the fast forward mode. Conversely, where plural music pieces are to be picked up, it is necessary to detect an inter-music piece space not only during the fast forward mode, but also during the playback mode. Therefore, it has become impossible to simply treat low frequency noises such as hums arising from an inter-music piece space.